1. Field of the Invention
The present invention relates to a method of making a package structure, particularly to a method of making a package structure by dicing a wafer from the backside surface thereof.
2. Description of the Related Art
FIG. 1 shows a cross sectional view of a conventional wafer level package structure. The conventional wafer level package structure is made by the following steps.
First, a first wafer 10 having an active surface 12 and a backside surface 14 is provided, and the active surface 12 has a plurality of scribe lines 16 defining a plurality of chips 18. Each chip 18 has an annular body 20, a plurality of pads 22 and a micro mechanism 24 thereon. The material of the annular body 20 is usually epoxy resin.
The micro mechanism 24 is disposed in the cavity defined by the annular body 20, and can be a micro active device (for example, integrated circuit, micro mechanical device or moving device) or a micro passive device (for example, sensor, capacitor or resistor). Taking a microlens set for example, the microlens set comprises: a supporting portion 241, a hinge 242 and a microlens 243. One end of the supporting portion 241 is connected to the chip 18. The hinge 242 is disposed at the other end of the supporting portion 241. One end of the microlens 243 is connected to the hinge 242 so that the hinge 242 can be a rotating center of the microlens 243.
The pads 22 are disposed outside the cavity defined by the annular body 20 and are used for electrically connecting to an outside circuit (not shown in the figure) after dicing process.
Then, a second wafer 25 having an upper surface 28 and a lower surface 26 is provided. Then, the second wafer 25 is covered and joined to the first wafer 10, and the lower surface 26 of the second wafer 25 faces the active surface 12 of the first wafer 10 to form a plurality of cavities defined by the annular body 20. The micro mechanism 24 is inside the cavity.
Finally, the first wafer 10 and the second wafer 25 are diced by utilizing the blade 34,36 to form a wafer level package structure 38 having a cavity.
In the conventional method, the lower surface 26 of the second wafer 25 faces the active surface 12 of the first wafer 10, and the process of dicing the first wafer 10 from its backside surface 14 would be very difficult because the scribe lines 16 are on the active surface 12 and the first wafer 10 is opaque.
Consequently, there is an existing need for a novel and improved method of making a package structure to solve the above-mentioned problem.